from __future__ import annotations

from pathlib import Path

from generator.score import copy_source_voices, make_arranged_document, make_measure, reidentify, slugify, source_staff, write_json
from generator.musicxml import load_musicxml
from generator.practice.guitar import transpose_guitar_practice
from generator.transposition import TARGET_KEYS, transpose_document

def practice_document(document: dict) -> dict:
  staff = source_staff(document)
  source_measures = staff.get("measures")
  if not isinstance(source_measures, list):
    raise ValueError("practice source must contain measures")
  measures: list[dict] = []
  for index, measure in enumerate(source_measure for source_measure in source_measures if isinstance(source_measure, dict)):
    voices = copy_source_voices(measure, strip_lyrics=True)
    output_measure = make_measure(
      f"measure-{index + 1}",
      measure,
      [],
      section_label=str(measure.get("section_label", "")),
    )
    output_measure['voices'] = voices
    measures.append(output_measure)
  tuplets = reidentify(measures, staff.get('tuplets', []))
  result = make_arranged_document(
    document,
    staff,
    staff_id="staff-arranged-practice",
    staff_name="Practice",
    role="vocal",
    arrangement_part_type="practice",
    measures=measures,
    tuplets=tuplets,
    octave_shifts=staff.get('octave_shifts', []),
  )
  result['metadata'].setdefault('authored_key_signature', document['metadata']['key_signature'])
  return result

def key_file_name(key: str) -> str:
  return slugify(key.replace("#", "sharp")) + ".json"

def generate_chord_practice(source_path: Path, source_root: Path, output_dir: Path) -> int:
  return generate_key_variants(source_path, source_root, output_dir, 'chord')

def generate_melody_practice(source_path: Path, source_root: Path, output_dir: Path) -> int:
  return generate_key_variants(source_path, source_root, output_dir, 'melody')

def generate_key_variants(source_path: Path, source_root: Path, output_dir: Path, practice_type: str) -> int:
  base_document = practice_document(load_musicxml(source_path))
  relative = source_path.relative_to(source_root)
  lesson_group = relative.parent.name
  exercise_id = slugify(source_path.stem)
  count = 0
  for key in TARGET_KEYS:
    try:
      variant = transpose_guitar_practice(base_document, key) if practice_type == 'chord' else transpose_document(base_document, key)
    except ValueError as error:
      raise ValueError(f'{source_path}, target key {key}: {error}') from error
    write_json(output_dir / practice_type / lesson_group / exercise_id / key_file_name(key), variant)
    count += 1
  return count

def generate_practice_scores(source_dir: Path, output_dir: Path) -> int:
  if not source_dir.exists():
    return 0
  sources = sorted(source_dir.rglob('*.xml'))
  destinations: dict[Path, Path] = {}
  for path in sources:
    parts = path.relative_to(source_dir).parts
    if len(parts) != 3 or parts[0] not in ('chord', 'melody'):
      raise ValueError(f'{path}: practice source must be stored as practice/<chord|melody>/<lesson_group>/<exercise>.xml')
    destination = Path(parts[0]) / parts[1] / slugify(path.stem)
    if destination in destinations:
      raise ValueError(f'{path}: practice output path collides with {destinations[destination]}: {destination}')
    destinations[destination] = path
  count = 0
  for destination, path in destinations.items():
    practice_type = destination.parts[0]
    count += generate_key_variants(path, source_dir / practice_type, output_dir, practice_type)
  return count